How badly would a plane like this perform?

[Shortround6]

Originally Posted by davparlr

I have read that Hughes had received some classified data on the 1535 performance surreptitiously. He may have been more comfortable with that engine than with the 1830. Also, as you have pointed out, the area increase of the 1830 (with only 1000 hp available at the time) would have had to be boosted to 1200 to equal the record breaking speed (my argument was that the rated power was much higher and thus more militarily acceptable), something he may have been more unsure of. He was, of course successful in boosting the 1535 40% (with help from 100 octane gas), if he would have done that with the 1830, he could have had quite a bit more power.

I believe the story went that on visit to the P&W factory he was left alone with the data in an office after the employee who wasn't "supposed" to show him the data was "called down the hall" for an extended period of time. Given that "lack" of co-operaton I doubt that Hughes couldn't have gotten similar information on the R-1830 if he wanted it.

I believe Jimmy Dolittle was supposed to have gotten an R-1340 up to 900hp on 100 octane fuel in testing in the very early 30s.
THese early HP ratings just showed the potential of the 100 octane fuel however. Getting the engines to hold together at these power levels for more than a few moments ( or to be able to hold cylinder temperature limts in any but optimium conditions) took a bit more work.

Streamlineing wasn't as well understood in the early-mid thirties as it was even in 1940. A lack of large scale, high speed wind tunnels ment that it was hard to test therorys. A number of racing planes were built to take both Wasp JR and Wasp engines interchangably to suit the costomers ideas on frontal area vrs power. ANd perhaps fuel consumption on long flights?

Hughe's record cross country flight was probably planned to use a an approximatly 20,000 ft cruising altitude. Benny Howard had won the Bendix race the year before cruising at 22,000ft, while on oxogen. Hughes plane was equiped with oxogen but a malfuction in the equipment almost caused him to black-out.
Actual cruising altitude may be unkown. Hughes had made 12 trips west to east as a co-pilot in DC-3s and had flown Jackie Cochran's Northrop Gamma to a west-east record the year before.

Since I don't know what certificate the Hughes racer flew under (experimental? group 2?) we don't really know what it was stressed for. SOme of these cross country planes took off heavily loaded with fuel ( a bit like a ferry flight and so thier "gross" weight might relate more to a fighter with carring full over load ferry tanks. For instance, The Mustang was rated at 8 "G"s but that was at 8,000lbs. To get the Mustangs "G" rating at other weights divide the weight into 64,000. ("8"s x 8,000lbs). For a tak-off weight of 12,400lbs the Mustang would have a "G" rating of 5.16 not figuring for local load limits on the attachment points or center of gravity issues.
Going back to the Hughes Racer if it's max gross weight was 5,492lb on the cross country flight we have no idea if the plane was stressed for any but the most gentle manuevers at such a loading. We do that bombers are desinged to a lower "g" loading than fighters and we know that currently the load factor for commercial light planes is 3.8 in the normal and commuter catigories, 4.4 for utility and 6 for acrobatic. Going back to the 1930s the regulations may have been a bit more lax, especially for a one-off special purpose airplane. On the other hand with high speed flight and the resultant stesses in it's infancy the engineers just might have erred on the side of caution and built the plane just a bit heavier than need be.

I did use the Brewster Buffalo as weight comparison becasue it is the only plane that is close to the weight of the hughes that I have a good weight break down for.

More later.

[FLYBOYJ]

Originally Posted by Shortround6

Since I don't know what certificate the Hughes racer flew under (experimental? group 2?) we don't really know what it was stressed for.

Hughes' racer was certificated under the old CARs experimental. What do you mean by group 2?

[Shortround6]

Actually I don't know

What I do know is that in Joseph Juptner's series on U.S. Civil aircraft (of Approved type Certificates) in volume #9 There is a chapter on planes that had "Group two approval" instead of a full Approved type Certificate. As described in the introduction to this chapter.

"....(Group 2) was usually awarded to an airplane that be built either in one or two examples only, a limited quantity for test and evaluation, or for some predetermined number of airplanes; this approval was also awarded for certain modifications (such as a different engine, increased, decreased, or rearrenged seating, major interior changes, increased fuel capacity, etc.) of a standard type airplane already in approved (ATC) production."

It does not say what the differences are. I will note that while a few long distance record setting planes are in this chapter there don't appear to be any of the Thompson trophy racers.

[Juha]

As a side note
There was a racer based fighter in service 1939-40, namely Caudron C.714, but it wasn’t a success. Rather fast if compared to M.S. 406 but underpowered, so lousy climber and rather unmanoeuvrable. So a failure as a fighter.

Juha